I propose to continue along the path of my prior work in cancer epidemiology. That work will entail: 1) Analyses of routinely-collected data on cancer incidence. Local and national data will be used, both to generate clues as to the etiologies of cancer and to address practical issues of cancer prevention. 2) Cohort and population-based case-control studies of cancer. In addition to concluding a number of studies begun during the first cycle of funding from the Outstanding Investigator Grant, I plan to initiate others, likely including studies of: a) ovarian cancer in relation to galactose consumption and metabolism; and b) subsequent cancer incidence among women with infertility, with particular attention given to the type of infertility and its treatment. With colleagues in the laboratory, I will continue to explore ways of more precisely characterizing exposure or susceptibility that can be put to use in epidemiologic studies. 3) Refinement of epidemiologic methods relevant to the study of cancer. Emphasis will be given to development of analytic strategies to minimize bias in case-control studies which evaluate the efficacy of cancer screening modalities.